1. Field of the Present Invention
The present invention generally relates to graphic display systems, and more particularly, to multi-processor graphic display systems.
2. History of Related Art
In a three-dimensional graphic display system (interface), such as that defined by PHIGS (Programmer's Hierarchical Interactive Graphics System) or the like, data is received by the system in the form of a structure. This structure is evaluated at the time of drawing so that a string of drawing instructions is generated therefrom. This string of drawing instructions is composed of attributes and primitives. Attributes are stored in a TSL (Traverse State List) as attribute items. During a draw operation on a computer display, primitives use the attributes in the TSL. In the case where these operations are to be performed in parallel by a multiprocessor system, a processing element (processor) is assigned a primitive so that execution can be achieved with high efficiency. In this case, each processing element to which a primitive is assigned must contain a copy of the contents of the TSL when the primitive is assigned thereto. To do so, the processing element must copy the TSL at the time of assignment to its private region each time the primitive is processed. Since the capacity of the TSL is generally 1000 bytes or more, overhead increases by virtue of the increase in the traffic on the bus, and the like. Therefore, the advantage of multiprocessor-based high-speed processing deteriorates.
A method is needed not only for copying the TSL when the primitive is assigned to a processing element, but also a method wherein the respective processing elements independently interpret and execute the primitives. This is called a symmetry system. (The symmetry system is introduced in "Execution performance evaluation on multiprocessor of geometry operation for the processing structure of PHIGS" by Takashi Matsumoto, Kei Kawase, and Takao Moriyama: Parallel processing symposium JSPP'92, p. 375-382).